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fe14a332e4
Summary:
If the trip count of a specific backedge is `N`, then we know that
backedge is effectively guarded by the condition `{0,+,1} u< N`. This
change teaches SCEV to use this condition to prove things in
`isLoopBackedgeGuardedByCond`.
Depends on D12948
Depends on D12949
The original checkin, r248608 had to be backed out due to an issue with
a ObjCXX unit test. That issue is now fixed, so re-landing.
Reviewers: atrick, reames, majnemer, hfinkel
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D12950
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248638 91177308-0d34-0410-b5e6-96231b3b80d8
24 lines
655 B
LLVM
24 lines
655 B
LLVM
; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
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; PR4569
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define i16 @main() nounwind {
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entry:
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br label %bb.i
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bb.i: ; preds = %bb1.i, %bb.nph
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%l_95.0.i1 = phi i8 [ %tmp1, %bb.i ], [ 0, %entry ]
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; This cast shouldn't be folded into the addrec.
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; CHECK: %tmp = zext i8 %l_95.0.i1 to i16
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; CHECK: --> (zext i8 {0,+,-1}<nw><%bb.i> to i16){{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: 2
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%tmp = zext i8 %l_95.0.i1 to i16
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%tmp1 = add i8 %l_95.0.i1, -1
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%phitmp = icmp eq i8 %tmp1, 1
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br i1 %phitmp, label %bb1.i.func_36.exit_crit_edge, label %bb.i
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bb1.i.func_36.exit_crit_edge:
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ret i16 %tmp
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}
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